This invention relates to an electrical resistance type deicer heater for use on propeller blades, helicopter rotor blades, etc. utilizing non-metallic and non-conductive blade structures such as reinforced fiberglass rather than the conventional metal structures which are standard in the art. It is well known to use electrical deicer heaters to remove ice from the blades, the necessary power being supplied in a conventional manner from the aircraft itself. In a typical prior art structure, the electrical resistance heater whether made from discrete wires or from an etched foil, was encapsulated in a sandwich between layers of non-conducting materials and was affixed to the blade in the desired location, typically as shown in U.S. Pat. No. 4,386,749. Such deicers, because of their weight, required careful placement of the heater to ensure that the propeller or rotor will remain in static and dynamic balance.
With the advent of improved propeller technology, it has been determined that a light weight and extremely durable composite construction utilizing little or no metal can be fabricated to produce a propeller blade capable of being rotated at the desired high speeds while securing all of the desired advantages of lighter weight, resistance to erosion in use, etc.
In order to devise suitable deicing heaters for use with such composite blades and rotors, each heater must avoid introducing unwanted mass while retaining the durability and reliability of the prior art. It is therefore a primary object of this invention to provide a deicer heater of reduced cross sectional thickness and of lighter weight than conventional deicers without sacrificing durability and serviceability.
It is another object of this invention to provide a heater of the electrical resistance type which reduces the cost of the deicer unit by requiring less material and less labor while retaining the advantages of durability and resistance to erosion, etc.
It is still a further object of this invention to provide a deicer pad that can be easily removed after extensive use resulting in severe wear.
Other objects will be in part obvious and in part pointed out in more detail hereinafter.
A better understanding of the objects, advantages, features, properties and relations of the invention will be obtained from the following detailed description and accompanying drawings which set forth certain illustrative embodiments and are indicative of the ways in which the principles of the invention are employed.